A Liquid-Crystal Display (LCD) display screen is a display device that displays an image by controlling a rotation direction of liquid crystal molecules by means of changing a voltage. The LCD display screen has advantages of low power consumption, long service time, and the like. Therefore, in the prior art, the LCD display screen has become more widely used as a display apparatus of a terminal, such as a mobile phone or a tablet computer.
A core of the LCD display screen is an LCD optical module. The LCD optical module includes an upper-layer glass substrate, a lower-layer glass substrate, and a liquid crystal cell that is disposed between the two layers of glass substrates. A thin film transistor is disposed on the lower-layer glass substrate, and a color filter is disposed on the upper-layer glass substrate. By changing a signal and a voltage of the thin film transistor, a rotation direction of liquid crystal molecules in the liquid crystal cell may be controlled, and light incident from the lower-layer glass substrate may be controlled to emit from the upper-layer glass substrate, so that an image is displayed.
The LCD optical module itself does not emit light. Therefore, to implement that light emits from the upper-layer glass substrate of the LCD display screen, a light source is used to provide backlight for the LCD display screen, so that light emitted from the light source is incident from the lower-layer glass substrate of the LCD display screen. An Light Emitting Diode (LED) has advantages of a small size, low power consumption, and the like. Therefore, in the prior art, the LED is usually used to provide backlight for the LCD optical module. The LED is a point light source. Therefore, to ensure uniform luminance of backlight provided by the LED, a light guide plate is further required to diffuse light emitted from the LED, so that the LED is transformed from a point light source to an area light source, and the area light source is used to provide backlight for the LCD optical module.
With continuous progress of technologies, an area of an LCD display screen keeps increasing, and correspondingly, an area of an LCD optical module also keeps increasing. Because an area of an area light source transformed from an LED point light source is limited, with a continuous increase in the area of the LCD display screen, there is an increasing quantity of LEDs, used to provide backlight for the LCD optical module, in the LCD display screen. However, an increase in a quantity of LEDs leads to an increase in power consumption of the LCD display screen.